The present invention relates to improvements in connectors for profiled bars and analogous structural members. More particularly, the invention relates to improvements in connectors which can be used to separably couple one or more flanges or like parts of a first profiled member to a second profiled member. Such connectors can be used with advantage in the construction industry to separably secure substantially horizontal beams, bars or like components to vertical or otherwise inclined bars, beams or analogous members.
German Pat. No. 29 41 008 to Stenemann discloses a connector wherein a single jaw is movable away from a fixed retainer and is also retractible so that it can be pivoted or otherwise moved away from the fixed retainer in order to overlie a flange of a profiled member to be thereupon moved rearwardly (away from the profiled member) in order to move into requisite engagement with the inner or rear side of the flange. The means for retracting the jaw includes a rotary eccentric, and a stationary wedge is provided to move the jaw away from the fixed retainer in response to retraction of the jaw under the action of the eccentric. The eccentric is in direct motion transmitting engagement with the retractible jaw so that the wear upon the jaw is rather pronounced and can result in unpredictable movements of the jaw relative to the fixed retainer.
Another drawback of the patented connector is that it cannot be readily installed in or on a second member (e.g., a horizontal bar or beam) which is to be coupled to the profiled member. As a rule, the second member has an open front side and defines an internal space which is accessible only from the front side so that the connector must be slipped into and thereupon properly anchored in the second member by entering the internal space by way of the open front side. Problems arise in connection with accessibility of the eccentric which must be rotated from time to time in order to deactivate or reactivate the connector. The arrangement is such that the major part of the connector is installed in the internal space of the second member in a first step, and the eccentric is installed thereafter so as to be placed into proper motion transmitting engagement with the jaw. Installation of the eccentric is followed by insertion thereinto of a rotary member in the form of a shaft which can be rotated by a tool in order to transmit torque to the eccentric. As a rule, the shaft is a press fit in the eccentric so as to avoid the need for additional parts which should hold the shaft in requisite engagement with the eccentric. The press fit must be sufficiently reliable in order to ensure that the shaft will remain in an optimum position after a large number of rotations in order to engage the jaw with or to disengage the jaw from a flange on the profiled member. Problems arise when the shaft must be expelled in order to afford access to remaining parts of the connector, i.e., to allow for extraction or expulsion of the connector from the internal space of the second member. In most instances, the expulsion of the shaft entails an at least partial destruction of the entire connector. The patent to Stenemann discloses the possibility of providing the shaft with a circumferential groove and of forcing the shaft into the opening of a leaf spring so that the material which surrounds the opening snaps into the groove whereby the shaft is held in a predetermined axial position. The patentee proposes to employ a hammer as a means for expelling the shaft from the leaf spring in order to allow for extraction or expulsion of the connector from the internal space of the second member. The application of blows by a hammer is not a satisfactory solution of the problem of providing a removable connector, especially since the space which is available for the application of the hammer blows is very small so that the hammer is likely to damage the parts which are adjacent the opening in the leaf spring.
German Offenlegungsschrift No. 31 28 595 of Hackenberg discloses a modified connector wherein the shaft and the eccentric are movable axially against the opposition of a spring. This renders it possible to shift the eccentric and the shaft axially in the interior of the second member, either for the purpose of installing such parts in the second member or of permitting their extraction from the second member. The eccentric and the shaft are held against relative axial movement or are made of one piece. It has been found that the proposal of Hackenberg is not entirely satisfactory because the application of stresses to the eccentric can result in disengagement of the shaft from the second member.
German Pat. No. 22 39 370 to Swoboda discloses a connector wherein, in accordance with a first embodiment, the eccentric has an eccentric hole for the shaft and these parts are coupled to each other in such a way that the eccentric is compelled to share all angular movements of the shaft. The connector has two retaining members which are provided with jaws in the form of hooks both movable toward or away from each other in response to direct engagement with the eccentric which has portions extending through holes provided therefor in the retaining members. A cylindrical displacing member is provided to spread the jaws apart in response to retraction of the retaining members as a result of rotation of the eccentric. The just described connector operates satisfactorily as long as the wear upon the eccentrics and the adjoining portions of the retaining members is nil or relatively small.
In accordance with a modification, the connector of Swoboda comprises retaining members each of which carries a jaw at one end and a cam face at the other end. The eccentric serves to shift an intermediate part which bears against the cam faces in order to move the jaws away from each other. The retaining members act not unlike levers and can be pivoted only in response to the application of large forces. Moreover, the means for rotating the eccentric must overcome pronounced resistance which is attributable to friction. Therefore, this modified version of the connector of Swoboda is less popular than the first embodiment. An additional reason for this is that the pivotable retaining members are not mounted for retraction against the inner sides of the flanges on the profiled member so that the connection which is established between the profiled member and the second member is not as reliable as is necessary in the building and certain other industries.
Published British patent application No. 2 119 054 of Zoller describes a connector wherein two eccentrics are in direct motion transmitting engagement with retaining members which are provided with jaws for engagement with the flanges of a profiled member. A further eccentric is employed to indirectly move a spreading element against the retaining members for the purpose of moving the jaws away from each other. This connector is not reliable because of the direct motion transmitting engagement between the eccentrics and the retaining members so that the jaws are likely to remain out of contact with the inner or rear sides of the respective flanges. The movements of the retaining members resemble those of a connecting rod which is caused to perform composite movements by the crank of a crankshaft. Such movements are not ideally suited to ensure that the jaws will be advanced into and will thereupon remain in requisite engagement with the respective flanges of the profiled member.
German Utility Model No. 73 41 204 of Gebrueder Vieler discloses a reciprocable retaining member which can be displaced by an eccentric.
Published European patent application No. 0 059 463 of Mertens discloses a connector with an exposed eccentric. A barrier is reciprocable to and from a position adjacent one axial end of the eccentric so that the latter cannot be moved axially.
German Utility Model No. 19 70 271 of Jankowski discloses a connector wherein the retaining members for the jaws are biased by or constitute springs so as to urge the jaws away from each other and into positions of overlap with the respective flanges of a profiled member. The eccentric acts directly upon the retaining members.